Ignition Interlock FAQs

How reliable are ignition interlocks?

• Currently, alcohol ignition interlocks are required by National Highway Traffic Safety Administration (NHTSA) standards to prevent a car from starting 90 percent of the time, if the BAC is .01 percentage points greater than the preset limit (.02 percentage points in extreme conditions). NHTSA is considering making these standards stricter^[1].

• Courts throughout the states have analyzed this issue and no state appellate court has overturned an interlock statute.

• On average, interlocks are about $70-150 to install and about $60-80 per month for monitoring and calibration. This is less than three dollars a day, less than the cost of one drink. In most jurisdictions, there are fines, program fees, insurance premium increases, assessments and other costs that are significantly more than the interlock fees. If it is a problem, in most states, interlock companies provide interlock devices for indigent offenders at reduced costs or an indigent fund is set up by the state to cover the costs for these offenders.

• This is possible, and there needs to be strict penalties for blowing into someone else’s alcohol ignition interlock or for having someone else blow into your device. However, currently interlocks are required to have anti-circumvention features that prevent such activity. One of these features is the running retest, which requires offenders to blow into the device at random intervals once the vehicle has been allowed to start. Furthermore, blowing into an interlock is a learned skill that requires specific training that would most likely be difficult for an impaired person to administer. There are also tamper-proof seals on interlocks to detect tampering.

• No, they are allowed to drive the vehicle as well; they simply must not drink and drive. Having an interlock installed on an offender’s vehicle actually allows the offender and his or her family members to continue to drive legally. Other sanctions like vehicle impoundment or immobilization do not allow for this.

• Although this is possible, when a convicted DUI offender violates society’s trust by committing a crime, he/she is responsible for the consequences of his/her actions. If an interlock is one of these consequences, then the offender is responsible for making sure those driving his or her vehicle do not drive intoxicated. State laws should also have provisions for an appeals process in which offenders can appeal failed tests. Finally, new technology includes identification systems that can detect who is blowing into the device.

• Individuals with low lung capacities due to having asthma or pulmonary disorders are generally able to provide the needed breath sample. If they can demonstrate that they are unable, the settings on the devices can be adjusted to account for this. Failing that,  medical waivers are allowed.

• No, the devices have temperature and air gauges to make sure this cannot occur.

• If this occurs, the individual can just wait a few minutes for the mouth alcohol to dissipate and blow again.

• Studies have shown that interlock devices decrease recidivism anywhere from 50-90 percent while installed on the vehicle. After they are removed, these rates tend to go back to normal. This most likely would not be the case if interlock programs were coupled with treatment and offenders were not allowed to have the device removed until they exercise a period of demonstrated compliance. An offender’s likelihood of reoffending is much greater if they fail tests during the interlock period. Unfortunately, in most states, offenders still automatically get the device removed at the end of the specified period, even if they failed a test the day before. It is essential that states add provisions for treatment and extended periods for non-compliance in order to make their laws more effective.

• This is not extremely common, but it does happen. It is imperative that state laws accommodate for this by mandating that all cars that the offender operates, not just owns, are equipped with an interlock. Also, offenders who choose not to drive should be required to have some other form of electronic monitoring, like continuous alcohol-sensing ankle bracelets. In Hancock County, Indiana, alcohol ignition interlock installation rates increased from 20 percent to 62 percent when the alternative was electronic monitoring (meaning that offenders who claimed not to have a car seemed to be able to find one when the alternative seemed more difficult). These policies alone reduced DWI rates by 40 percent for first offenders and 22 percent for repeat offenders.^[2]

• Some of the new advancements in interlock technology have not been well-publicized to the judiciary. As a result, some judges do not know how they work or do not understand that they are an effective sanction. This is why judicial education is so important because generally those judges who know the most about interlock technology are the ones who are using them most.

• Interlocks are hooked up to a vehicle’s starter system, not to the engine itself. The interlock does not have the ability to stop the vehicle once it is running for safety reasons. When a driver fails a running retest, the vehicle’s horn will honk and/or the lights will flash to alert law enforcement – the vehicle will not stop.

• The tests are not designed to be done while the car is actually rolling. Interlocks give people a few minutes – enough time to pull over – to perform the retest.